LDL peroxidation in adolescent female gymnasts

Physical exercise may in vivo promote an increase of free radical formation. Low-density lipoproteins (LDL) are highly susceptible to oxidation, probably because of their high polyunsaturated fatty acid content, since lipid oxidation is an important factor in the genesis and development of atherosclerosis. The aim of the present study is to evaluate the effect in a group of adolescent gymnasts, of intense and regular physical exercise on lipid profile and redox status.

All members of the Portuguese National Team of Rhythm Gymnastics (1996) (n = 20).

1. Clinical evaluation 1.1 Anthropometric evaluation: weight, height, triceps, biceps, subscapular and supra- and supra-iliac skinfolds. NCHS were used as the standard of reference for weight and height, and Frisancho for the sum of skinfolds; 1.2. Evaluation of nutritional status (Quetelet body mass index) and body composition (Durnin and Siri). 2. Evaluation of biological parameters: a blood sample was collected after 12 hours fasting and 24 hours detraining, to evaluate: 2.1 Lipid profile: total cholesterol, high (HDL) and low (LDL) density lipoproteins, triglycerides, apolipoproteins A1 and B, were measured using internationally recommended laboratory methods; 2.2. Plasma trace elements: zinc, copper and selenium, by atomic absorption; 2.3 Red blood cell enzymes; transmembranar reductase (TMR), metahemoglobin reductase (MethaHbRed) and acid phosphatase, by spectrophotometry; 2.4. Redox status: MDA and MDA-LDL were evaluated by spectrophotometry. 3. Evaluation of eating habits: 24 hr recall.

Chronological age is 14.3 +/- 1.7 years. Nutritional assessment shows a mean value for height near the 50th percentile (99% +/- 3.8), and low mean values respectively for BMI (89.3% +/- 9) and sum of triceps and subscapular skinfolds (51.9% +/- 14). Study of lipid profile shows low mean values for total cholesterol (162.3 mg/dl +/- 27.7) LDL-cholesterol (87.6 mg/dl +/- 22.6) and Apo B (64.4 mg/dl +/- 11.5), but high values for HDL-cholesterol (61.3 mg/dl +/- 14.5) and Apo A1 (173.1 mg/dl +/- 25.1). We observe higher values for total cholesterol and LDL-cholesterol in those with lower Cu plasmatic levels. We also observe a negative significative correlation between MDA-LDL and Zn (r = -0.469), Cu (r = -0.524) and RTM (r = -0.608).

The AA concluded that in this group of gymnasts intense physical exercise induces, a favorable lipid profile, but a clear susceptibility to LDL peroxidation in those with lower plasma Cu and Zn values. It is possible that the negative correlation observed between MDA-LDL and TMR is caused by higher consumption of TMR induced by the action of exercise on the oxidative system.